Add support for executing the FreeBSD 1/i386 a.out binaries on amd64.

In particular:
- implement compat shims for old stat(2) variants and ogetdirentries(2);
- implement delivery of signals with ancient stack frame layout and
  corresponding sigreturn(2);
- implement old getpagesize(2);
- provide a user-mode trampoline and LDT call gate for lcall $7,$0;
- port a.out image activator and connect it to the build as a module
  on amd64.

The changes are hidden under COMPAT_43.

MFC after:   1 month

4 files changed, 15 insertions, 8 deletions

diff --git a/sys/compat/ia32/ia32_genassym.c b/sys/compat/ia32/ia32_genassym.c
index 84fb648..5462a8b 100644
--- a/sys/compat/ia32/ia32_genassym.c
+++ b/sys/compat/ia32/ia32_genassym.c
@@ -13,6 +13,9 @@ __FBSDID("$FreeBSD$");
 
 ASSYM(IA32_SIGF_HANDLER, offsetof(struct ia32_sigframe, sf_ah));
 ASSYM(IA32_SIGF_UC, offsetof(struct ia32_sigframe, sf_uc));
+#ifdef COMPAT_43
+ASSYM(IA32_SIGF_SC, offsetof(struct ia32_sigframe3, sf_siginfo.si_sc));
+#endif
 ASSYM(IA32_UC_GS, offsetof(struct ia32_ucontext, uc_mcontext.mc_gs));
 ASSYM(IA32_UC_FS, offsetof(struct ia32_ucontext, uc_mcontext.mc_fs));
 ASSYM(IA32_UC_ES, offsetof(struct ia32_ucontext, uc_mcontext.mc_es));
diff --git a/sys/compat/ia32/ia32_signal.h b/sys/compat/ia32/ia32_signal.h
index 757e384..0c54caf 100644
--- a/sys/compat/ia32/ia32_signal.h
+++ b/sys/compat/ia32/ia32_signal.h
@@ -112,7 +112,7 @@ struct ia32_ucontext4 {
 };
 #endif
 
-#ifdef COMPAT_FREEBSD3
+#ifdef COMPAT_43
 struct ia32_sigcontext3 {
 	u_int32_t	sc_onstack;
 	u_int32_t	sc_mask;
@@ -165,7 +165,7 @@ struct ia32_sigframe {
 	struct siginfo32	sf_si;		/* = *sf_siginfo (SA_SIGINFO case) */
 };
 
-#ifdef COMPAT_FREEBSD3
+#ifdef COMPAT_43
 struct ia32_siginfo3 {
 	struct ia32_sigcontext3 si_sc;
 	int			si_signo;
@@ -186,10 +186,15 @@ struct ksiginfo;
 struct image_params;
 extern char ia32_sigcode[];
 extern char freebsd4_ia32_sigcode[];
+extern char ia32_osigcode[];
+extern char lcall_tramp;
 extern int sz_ia32_sigcode;
 extern int sz_freebsd4_ia32_sigcode;
-extern void ia32_sendsig(sig_t, struct ksiginfo *, sigset_t *);
-extern void ia32_setregs(struct thread *td, struct image_params *imgp,
+extern int sz_ia32_osigcode;
+extern int sz_lcall_tramp;
+void ia32_sendsig(sig_t, struct ksiginfo *, sigset_t *);
+void ia32_setregs(struct thread *td, struct image_params *imgp,
     u_long stack);
+int setup_lcall_gate(void);
 
 #endif
diff --git a/sys/compat/ia32/ia32_sysvec.c b/sys/compat/ia32/ia32_sysvec.c
index a7790ef..c7edac4 100644
--- a/sys/compat/ia32/ia32_sysvec.c
+++ b/sys/compat/ia32/ia32_sysvec.c
@@ -95,14 +95,12 @@ CTASSERT(sizeof(struct ia32_sigframe4) == 408);
 
 extern const char *freebsd32_syscallnames[];
 
-static void ia32_fixlimit(struct rlimit *rl, int which);
-
 SYSCTL_NODE(_compat, OID_AUTO, ia32, CTLFLAG_RW, 0, "ia32 mode");
 
 static u_long	ia32_maxdsiz = IA32_MAXDSIZ;
 SYSCTL_ULONG(_compat_ia32, OID_AUTO, maxdsiz, CTLFLAG_RW, &ia32_maxdsiz, 0, "");
 TUNABLE_ULONG("compat.ia32.maxdsiz", &ia32_maxdsiz);
-static u_long	ia32_maxssiz = IA32_MAXSSIZ;
+u_long	ia32_maxssiz = IA32_MAXSSIZ;
 SYSCTL_ULONG(_compat_ia32, OID_AUTO, maxssiz, CTLFLAG_RW, &ia32_maxssiz, 0, "");
 TUNABLE_ULONG("compat.ia32.maxssiz", &ia32_maxssiz);
 static u_long	ia32_maxvmem = IA32_MAXVMEM;
@@ -206,7 +204,7 @@ elf32_dump_thread(struct thread *td __unused, void *dst __unused,
 {
 }
 
-static void
+void
 ia32_fixlimit(struct rlimit *rl, int which)
 {
 
diff --git a/sys/compat/ia32/ia32_util.h b/sys/compat/ia32/ia32_util.h
index 4355daa..f153492 100644
--- a/sys/compat/ia32/ia32_util.h
+++ b/sys/compat/ia32/ia32_util.h
@@ -58,5 +58,6 @@
 struct syscall_args;
 int ia32_fetch_syscall_args(struct thread *td, struct syscall_args *sa);
 void ia32_set_syscall_retval(struct thread *, int);
+void ia32_fixlimit(struct rlimit *rl, int which);
 
 #endif